[FIX] ir.qweb: rendering non-string attributes could cause unicode errors (Issue #282)

This occurs because werkzeug.utils.escape() auto-casts
non-basestring values to unicode, while we expect to be
working with bytestrings only.
So when evaluating attribute values, make sure we always
return bytestring values, never int, bool or unicode.
[FIX] website_crm: when there is an error in required field, user_id=False in the controller overwrite the user_id browse record to display the contact form template.
Merge pull request #405 from odoo-dev/saas-5-fix-website-contact-form-chm

[FIX] website_crm: when there is an error in required field, user_id=False in the controller overwrite the user_id browse record to display the contact form template.